On Friday

On Friday, Amanda bought 5 ⅙ kg of dog food. She used 1 ¼ kg of it on her dog Gunner and 2 ½ kg of it on her dog Connor. How many kilograms of dog food did Amanda have left?

Correct answer:

x =  1 ⁵⁄₁₂ = 17/12 kg

Step-by-step explanation:

$$\begin{gathered} t=5\frac{1}{6}=5+\frac{1}{6}=\frac{5\cdot 6+1}{6}=\frac{30+1}{6}=\frac{31}{6}\doteq 5.1667\text{kg} \\ g=1\frac{1}{4}=1+\frac{1}{4}=\frac{1\cdot 4+1}{4}=\frac{4+1}{4}=\frac{5}{4}=1.25\text{kg} \\ c=2\frac{1}{2}=2+\frac{1}{2}=\frac{2\cdot 2+1}{2}=\frac{4+1}{2}=\frac{5}{2}=2.5\text{kg} \\ x=t-g-c=\frac{31}{6}-\frac{5}{4}-\frac{5}{2}=\frac{62}{12}-\frac{15}{12}-\frac{30}{12}=\frac{62-15-30}{12}=\frac{17}{12}=\frac{17}{12}\text{kg}=1\frac{5}{12}\text{kg}=1.4167\text{kg} \end{gathered}$$

Try another example